A medical imaging system employs a transesophageal probe (20) including an ultrasound transducer (21) for scanning a patient's heart and atrial electrode(s) (22) for generating atrial electrocardiogram signal(s) predominately indicative of electrical activity of atrium chambers of the patient's heart. The medical imaging system further employs ventricular electrode(s) (23) for generating ventricular electrocardiogram signal(s) predominately indicative of electrical activity of ventricle chambers of the patient's heart. The medical imaging system further employs an electrocardiogram machine (30) for generating an electrocardiogram waveform based on the indicated electrical activities of the patient's heart, and for generating a cardiac gating signal representative of a cyclical cardiac phase period of the electrocardiogram waveform. The medical imaging system further employs an ultrasound machine (40) for reconstructing an ultrasound image of the patient's heart encompassing a time segment or an entirety of the cyclical cardiac phase period.